Extreme wave indexes estimate the occurrence of extreme wave events in coastal and oceanic waters. Extreme wave indexes estimate the number of times a significant wave height exceeds one of three threshold values for at least 12 hours in 24 marine regions. The three wave-height thresholds are four metres, six metres, and eight metres.
This indicator estimates the exceedances of wave-height thresholds for each year from 2008 to 2015 in coastal areas.
Significant wave height is a measure of the ‘typical’ wave height in a place over a time period. It is four times the standard deviation of the water surface if, for example, you were to measure water moving up and down a jetty piling for an hour. The largest individual wave will typically have a height around twice the significant wave height.
We use three wave-height thresholds because of the regional variation in extreme wave events. In general, the north experiences less exposure to consistently strong winds, and the waves generated by them, than the south. Four-metre tall waves are considered extreme in the northern-most parts of New Zealand but are more common in the south. For the southern-most parts of New Zealand, eight-metre waves better represent extreme wave events.

The Hector’s and Māui dolphins are subspecies of the small dolphin Cephalorhynchus hectori. These coastal dolphins are endemic to New Zealand (not found anywhere else). Māui dolphins are found on the west coast of the North Island, most often between Maunganui Bluff, north of Dargaville, and New Plymouth. Hector’s dolphins are mostly found around the South Island. Both subspecies are threatened with extinction. The Hector’s dolphin is classified as nationally endangered, while the Māui dolphin is nationally critical. Dolphins can become entangled in fishing gear used by both commercial and recreational fishers, with set nets posing a particularly high risk. Reporting the bycatch of protected species helps us understand the pressures our protected marine species face from fishing.
We report on two aspects of Hector’s and Māui dolphin deaths based on data extracted from the Department of Conservation (DOC) Incident Database for 1921–2015: the number of dolphin deaths by cause of death, including a comparison of deaths over 1996–2015; and the number of dolphin deaths from entanglement by type of fishing gear.

Sea lions and fur seals are the protected species most directly affected by fisheries in New Zealand waters, along with seabirds and dolphins. Trawling poses a risk to both species. Fur seals can also be captured by other fishing gear, including long lines. Estimating the bycatch of sea lions and fur seals indicates the pressures they face from current fishing practices.
The New Zealand sea lion Phocarctos hookeri is threatened with extinction and is classified as nationally critical. Its population is steadily falling at some breeding locations (Baker et al, 2010). Fisheries are one of the pressures on the species.
The Fisheries Act 1996 designates this species as protected and requires mitigation measures to reduce bycatch (Ministry for Primary Industries, 2014).

Sea lions and fur seals are the protected species most directly affected by fisheries in New Zealand waters, along with seabirds and dolphins. Trawling poses a risk to both species. Fur seals can also be captured by other fishing gear, including long lines. Estimating the bycatch of sea lions and fur seals indicates the pressures they face from current fishing practices.
The New Zealand fur seal Arctocephalus forsteri is classified as not threatened with extinction and its population appears to be increasing and extending back into its historical range (where they were commonly found) (Baker et al, 2010). They have a wide distribution, but are more common in the southern parts of New Zealand.
The Fisheries Act 1996 designates the New Zealand fur seal as protected and requires mitigation measures to reduce bycatch (Ministry for Primary Industries, 2014).

Our fish stocks are affected by commercial, customary, and recreational fishing, and environmental pressures (eg ocean temperature, acidity, and productivity). The Ministry for Primary Industries uses three performance measures to assess influences on fish stocks: a soft limit (below which a rebuilding plan is required), a hard limit (below which closing a fishery should be considered), and an overfishing threshold (where the rate of extraction is higher than the rate of replenishment).

Our fish stocks are affected by commercial, customary, and recreational fishing, and environmental pressures (eg ocean temperature, acidity, and productivity). The Ministry for Primary Industries uses three performance measures to assess influences on fish stocks: a soft limit (below which a rebuilding plan is required), a hard limit (below which closing a fishery should be considered), and an overfishing threshold (where the rate of extraction is higher than the rate of replenishment).

Our fish stocks are affected by commercial, customary, and recreational fishing, and environmental pressures (eg ocean temperature, acidity, and productivity). The Ministry for Primary Industries uses three performance measures to assess influences on fish stocks: a soft limit (below which a rebuilding plan is required), a hard limit (below which closing a fishery should be considered), and an overfishing threshold (where the rate of extraction is higher than the rate of replenishment).

Marine mammals, seabirds, and shorebirds are indicator species for the state of our marine environment. A decreasing population can indicate that the ecosystem is degrading. New Zealand has a diverse range of marine species, many of which are endemic to (only breed in) New Zealand. They are apex species (near the top of the food chain) and can thrive only if their ecosystems are healthy.
This measure reports on the number of indigenous marine species that have had a genuine change in conservation status between two monitoring periods (2008–11 and 2012–14). A change in a species’ conservation status reflects a change in its risk of extinction.

The ocean storm index estimates the number of days in a year when wind speeds exceed gale and storm force on the Beaufort Scale. In a gale, sea conditions are rough and waves can be over six metres high. In a storm, waves can be over 10 metres high. To put this into context, on land a near gale would make walking difficult, and a storm would cause some damage to roofs, chimneys, and trees. Climate change could lead to changes in the frequency and intensity of storms. More frequent and intense storms will likely be a stressor for habitats and species.
The ocean storm index estimates the number of days that wind speeds exceed gale and storm force on the Beaufort Scale. The Beaufort Scale is a widely used international classification that rates sea conditions from 0 (calm) to 12 (hurricane). We report on estimated wind speeds broken down to:
- gales – measure 8 on the scale, have rough sea conditions with wind speeds of approximately 62–74 km per hour and wave heights of 5.5 metres
- storms – measure 10 on the scale, have wind speeds of approximately 89–102 km per hour and wave heights of 9–11.5 metres (McDonald & Parsons, 2016)

New Zealand’s four million km2 marine environment is diverse, with a range of coastal habitats and offshore seabed environments. We also have many marine species found only in New Zealand. Marine protected areas conserve or manage some of these unique habitats and species, while a range of other tools also provide marine protection. We report on the area covered by marine reserves as an indirect measure to understand the state of the marine environment.